Adrian - have a very good look at the customer's contacts and check out the "Post, Email, SMS, List or Export?" part of http://www.openvpms.org/documentation/csh/1.9/reporting/reminder

We are in the process of switching to email reminders and I have had to build a set of reports to check the reminder purpose settings on all customer contacts, and a set of SQL statements to clean things up.

For us (switching to email reminders) the process has been:

1) check that all email addresses look valid

2) check that there is only one preferred email address per customer

3) clear all reminder purposes

4) set purpose Reminder for all preferred email contacts

5) set purpose Reminder on phone contacts for customers who do not have a preferred email contact

6) run report to print list all customers who do not have either one email address with purpose Reminder or one or more phone contacts with purpose Reminder set.
[Actually this generates a large list - since one does not have to worry about customers who do not have patients with reminders, I tweaked this to a version that only looks for customers with patients with current reminders who do not have either one email address with purpose Reminder or one or more phone contacts with purpose Reminder set. And the plan is to run this prior to doing the Reminder runs.]

In your case (SMS reminders), you probably want slightly different logic to the above.

However, the bottom line is to make sure that you have the reminder purposes set as you need them, and make sure that if you want to do other than list the reminder (ie you want to post, email, or sms) then you have only one contact of the appropriate type set with purpose reminder.

Regards, Tim G